TypeScript中GraphQL自定义标量用Regex.test()报Apollo运行时错误求助

我在TypeScript中创建GraphQL自定义标量，实现了serialize、parseValue和parseLiteral函数，想用正则表达式校验传入的值，但使用if (value.test(yearMonthDayRegex)) {}作为判断条件时，触发了Apollo运行时错误：

TypeError: value.test is not a function
            at GraphQLScalarType.coerceType (/Users/mej/Documents/elastigraph/elastigraph/packages/core/src/lib/gqlScalarTypes.ts:30:20)
            at coerceInputValueImpl (/Users/mej/Documents/elastigraph/elastigraph/node_modules/.pnpm/graphql@16.6.0/node_modules/graphql/utilities/coerceInputValue.js:151:26)
            at coerceInputValueImpl (/Users/mej/Documents/elastigraph/elastigraph/node_modules/.pnpm/graphql@16.6.0/node_modules/graphql/utilities/coerceInputValue.js:117:34)
            at coerceInputValueImpl (/Users/mej/Documents/elastigraph/elastigraph/node_modules/.pnpm/graphql@16.6.0/node_modules/graphql/utilities/coerceInputValue.js:117:34)
            at coerceInputValue (/Users/mej/Documents/elastigraph/elastigraph/node_modules/.pnpm/graphql@16.6.0/node_modules/graphql/utilities/coerceInputValue.js:32:10)
            at coerceVariableValues (/Users/mej/Documents/elastigraph/elastigraph/node_modules/.pnpm/graphql@16.6.0/node_modules/graphql/execution/values.js:132:69)
            at getVariableValues (/Users/mej/Documents/elastigraph/elastigraph/node_modules/.pnpm/graphql@16.6.0/node_modules/graphql/execution/values.js:45:21)
            at buildExecutionContext (/Users/mej/Documents/elastigraph/elastigraph/node_modules/.pnpm/graphql@16.6.0/node_modules/graphql/execution/execute.js:280:63)
            at execute (/Users/mej/Documents/elastigraph/elastigraph/node_modules/.pnpm/graphql@16.6.0/node_modules/graphql/execution/execute.js:116:22)
            at /Users/mej/Documents/elastigraph/elastigraph/node_modules/.pnpm/@envelop+core@3.0.6/node_modules/@envelop/core/cjs/orchestrator.js:376:33

我的正则表达式为：const yearMonthDayRegex = /^d{4}-(0?[1-9]|1[012])-(0?[1-9]|[12][0-9]|3[01])$/;

问题解决 #

1. 正则调用顺序错误
   报错的直接原因是搞反了正则方法的调用方式：test()是正则表达式对象的方法，需要用正则实例调用，传入要校验的字符串，正确写法是yearMonthDayRegex.test(value)，而非value.test(yearMonthDayRegex)。

2. 正则表达式语法错误
   正则里^d{4}中的d未转义，应写成^\d{4}，否则会匹配字面量字符d，而非数字0-9。

3. 前置类型校验
   在自定义标量的三个方法中，需先判断传入值的类型是否为字符串，避免非字符串类型触发额外错误。

修正后的示例代码 #

import { GraphQLScalarType, Kind } from 'graphql';

const yearMonthDayRegex = /^\d{4}-(0?[1-9]|1[012])-(0?[1-9]|[12][0-9]|3[01])$/;

export const DateScalar = new GraphQLScalarType({
  name: 'Date',
  description: '仅接受YYYY-MM-DD格式的日期字符串',
  serialize(value: unknown) {
    if (typeof value === 'string' && yearMonthDayRegex.test(value)) {
      return value;
    }
    throw new Error('日期格式不符合要求，必须为YYYY-MM-DD');
  },
  parseValue(value: unknown) {
    if (typeof value === 'string' && yearMonthDayRegex.test(value)) {
      return value;
    }
    throw new Error('日期格式不符合要求，必须为YYYY-MM-DD');
  },
  parseLiteral(ast) {
    if (ast.kind === Kind.STRING && yearMonthDayRegex.test(ast.value)) {
      return ast.value;
    }
    throw new Error('日期格式不符合要求，必须为YYYY-MM-DD');
  },
});

内容的提问来源于stack exchange，提问作者mojones101